Peer-to-peer (P2P) of Video-on-demand (VOD) service may be used to reduce bandwidth loading of video content provider. However, the internet service provider (ISP) may use Firewall to block P2P flow or to limit search efficiency and transmission rate of P2P service. Thus, the user device which is blocked by Firewall (which is also called “blocked user device”) has difficulty in exchanging data with public user devices outside the Firewall. Further, as P2P technology is advanced, the ISP will also enhance their Firewall.
Thus, how to efficiently provide VOD service in network is a target.